Numerical analysis of heat transfer and solid volume fraction profiles around a horizontal tube immersed in a supercritical water fluidized bed

Lu, Youjun; Zhang, Tianning; Dong, Xubin

doi:10.1016/j.applthermaleng.2015.09.026

Cited by 30 publications

(3 citation statements)

References 62 publications

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“…In 2013, Wei et al simulated residence time for feeding materials in a SCWFB by TFM, and the effects of feeding types and feeding rates were studied. Afterward, Lu et al , studied the wall-to-bed heat transfer with an immersed tube in SCWFB and a comparison was made with that in a gas–solid fluidized bed by TFM. The CFD-DEM method deals with the motion of particles by Newton’s law and it is capable of a detailed study at the particle level.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Wall-to-Bed Heat Transfer in a Supercritical Water Fluidized Bed by the Packet Approach

Zhang

2020

Ind. Eng. Chem. Res.

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Supercritical water fluidized bed (SCWFB) is a promising reactor to gasify coal or biomass with low pollution. In the present paper, attempts are made to model wall-to-bed heat transfer in a SCWFB by the packet renewal theory developed in traditional fluidized beds. The key parameters, such as the packet residence time near the wall, the fraction of total time with packet contact, and packet voidage, which are required for the packet approach, are obtained by the homemade capacitance probe for high temperature and pressure. To complete the wall-to-bed heat transfer model in a SCWFB, the physical properties of the packet are chosen properly and seven kinds of thermal conductivity models for the mixture are tested. A simplified spherical particle model is adopted to describe the thermal resistance between the wall and the packet. Then, a comparison is made between heat transfer coefficients by the model based on the packet renewal theory and heat transfer coefficients by the empirical correlation [ Zhang Zhang Int. J. Multiphase Flow20181092634]. It is found that they could match well with each other. The best fit can be observed when the Zehner and Schltinder thermal conductivity model is adopted, the relative error of which is 5.6% and the maximum relative error of which is less than 15%. Moreover, wall-to-packet heat transfer is considered to be dominant in a SCWFB.

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Section: Introductionmentioning

confidence: 99%

Modeling of Wall-to-Bed Heat Transfer in a Supercritical Water Fluidized Bed by the Packet Approach

Zhang

2020

Ind. Eng. Chem. Res.

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“…It is clear from the literature that, supercritical fluids are used in many branches of science and industries, for instance, chemical engineering, drug delivery, chromatography, power engineering, extraction and purification of chemical compounds, preparation of nanoparticles for medical benefit, aerospace engineering, etc. The detailed properties of various supercritical fluids including supercritical water and their advantages are found in some of the available literature [11][12][13][14][15][16][17][18][19][20][21]. In view of such interesting properties of supercritical water discussed above, the authors have chosen this fluid for the present study.…”

Section: Introductionmentioning

confidence: 99%

A numerical study of natural convection properties of supercritical water (H2O) using Redlich–Kwong equation of state

2019

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In this article, the Crank-Nicolson implicit finite difference method is utilized to obtain the numerical solutions of highly nonlinear coupled partial differential equations (PDEs) for the flow of supercritical fluid (SCF) over a vertical flat plate. Based on the equation of state (EOS) approach, suitable equations are derived to calculate the thermal expansion coefficient (b) values. Redlich-Kwong equation of state (RK-EOS), Peng-Robinson equation of state (PR-EOS), Van der Waals equation of state (VW-EOS) and Virial equation of state (Virial-EOS) are used in this study to evaluate b values. The calculated values of b based on RK-EOS is closer to the experimental values, which shows the greater accuracy of the RK-EOS over PR-EOS, VW-EOS and Virial-EOS models. Numerical simulations are performed for H 2 O in three regions namely subcritical, supercritical and near critical regions. The unsteady velocity, temperature, average heat and momentum transport coefficients for different values of reduced pressure and reduced temperature are discussed based on the numerical results and are shown graphically across the boundary layer.

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“…[21] Improvements in numerical techniques and computing power have provided opportunities to advance CFD application on simulating the reactions in a fluidized bed. Lu et al [22][23][24] studied the heat transfer and hydrodynamics in a fluidized bed using kinetic theory of granular flow without considering reactions. Due to the complexity of multiphase combustion process in fluidized bed which involves homogeneous and heterogeneous reaction process, only few literatures [25][26][27] considered CFD for combustion in fluidized bed while overlooking three dimensional effects.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation and optimization of an industrial fluid catalytic cracking regenerator

Tang

Silaen

et al. 2017

Applied Thermal Engineering

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Fluid catalytic cracking (FCC) is one of the most important conversion processes in petroleum refineries. FCC regenerator is a key part of an FCC unit to recover the solid catalyst reactivity by burning off the deposited coke on the catalyst. In this paper, a three-dimensional multi-phase, multi-species reacting flow computational fluid dynamics (CFD) model was established to simulate the flow and the reactions inside an FCC regenerator. The Euler-Euler approach, where the two phases (gas and solid) are considered to be continuous and fully interpenetrating, is employed. A modified drag force model was applied on the CFD model with appropriate influential cluster diameters of particle grouping phenomenon. The developed CFD model was validated by using plant data. With the validated CFD model, the flow characteristics and the inner-phase and inter-phase reactions were studied. The results showed that the effect of oxygen enrichment on the catalysts recovery efficiency was limited when the oxygen enrichment exceeded 5%.

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Numerical analysis of heat transfer and solid volume fraction profiles around a horizontal tube immersed in a supercritical water fluidized bed

Cited by 30 publications

References 62 publications

Modeling of Wall-to-Bed Heat Transfer in a Supercritical Water Fluidized Bed by the Packet Approach

Modeling of Wall-to-Bed Heat Transfer in a Supercritical Water Fluidized Bed by the Packet Approach

A numerical study of natural convection properties of supercritical water (H2O) using Redlich–Kwong equation of state

Numerical simulation and optimization of an industrial fluid catalytic cracking regenerator

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